#1 Practising and knowing your Charactermovement is the on side. The other side is switching between the different Novas. I usually use Shatter. On close maps with a lot of doorways and stuff i switch to vortex or lance. #2 use skull of dire ahamkara and nothing will kill you during your nova. I don't run this helmet. I try to blink around a corner and the Nove is out before they know whats going on. To counter supers, most times i let them come and pre fire the nova to the spot they will appear. I got killed during nova too. But most times its my fault because of beeing to predictable. #3 The Grenades aren't that powerful compared to other classes. But Axion bolt is so good for finishing weak opponents hiding or getting them out of their cover. When I'm going to engage an enemy a lot of times i first throw my axion before i start shooting. They are getting finished by the axion seeker before i fired my third shot with the Mida. Try to run Osiris with two or three Voidwalkers. Its like cat and mouse when they try to escape from the seekers and run directly in your line of fire. I think the Voidwalker works best when its played tactical. Don't spam Nades. First think what you want them to do. Kill them or get them out of cover? When anticipating enemys good its great to get the supers down instantly. On Big maps use Vortex mastery for letting your axion seekers chase them longer. On small maps use Bloom. Its great! i got double kills with one Melee. On a trials match i had a triple kill with one Axion Grenade exploding a weakened enemy.